1. Technical Field
The present invention relates to a reflective polarizing plate apparatus, an electro-optic apparatus, an optical apparatus, and a projector.
2. Related Art
There have been projectors known to use a reflective light modulating device. Some of the projectors include a wire-grid reflective polarizing plate.
JP-A-2008-180856 discloses a projection display system (projector) including reflective spatial light modulators, a color light illuminator, wire-grid polarizers, a light combining system, a supporting member for each color light flux disposed in the vicinity of a light-incident surface of the light combining system and having at least a first surface to which a wire-grid polarizer for the color light flux is attached and a second surface to which the reflective spatial light modulator for the color light flux is attached via a position adjusting mechanism, and a projection lens. Each of the wire-grid polarizers has a wire grid formed of metal lines disposed on one surface of an optical glass substrate, and the surface of the optical glass substrate where the wire grid is not formed is removably fixed to the first surface of the supporting member for the color light flux corresponding to the wire-grid polarizer by using a spring member for fixing the wire-grid polarizer.
Specifically, each of the wire-grid polarizers is placed on three protrusions in a deeper one of two recesses formed around a rectangular hole provided through the first surface of the corresponding supporting member, which has a triangularly columnar shape. Further, a sealing member is disposed on the shallower recess while overhanging over the deeper recess, and a plate spring member is disposed over the entire structure. Three pressing portions of the plate spring member that correspond to the protrusions perpendicularly press and fix the wire-grid polarizer, and a frame portion of the plate spring member presses and fixes the sealing member. The plate spring member is fixed to the triangularly columnar supporting member by hooking rectangular holes of the plate spring member to stubs formed on the lower and upper surfaces of the supporting member, whereby the pressing portions of the plate spring member apply a fixed load to the wire-grid polarizer. JP-A-2008-180856 states that the configuration described above can reduce the amount of misregistration and hence provide a highly stable, high-quality image.
In JP-A-2008-180856, the pressing portions of the plate spring member fix each of the wire-grid polarizers by applying a fixed load thereto in the direction perpendicular to a flat surface thereof, as described above. The thus fixed wire-grid polarizer, however, tends to rotate when an impact (including physical and thermal impact), vibration, or any other external force is applied thereto. The wire-grid polarizer (wire-grid reflective polarizing plate), when it is rotated in the plane thereof and hence angularly misaligned with a reflective light modulating device, can seriously cause decrease in contrast. A wire-grid reflective polarizing plate has another problem of distortion of the reflective polarizing plate itself resulting from the way it is pressed for fixation and hence degradation in optical characteristics of the reflective polarizing plate.
Further, in JP-A-2008-180856, since each of the wire-grid polarizers is fixed to the supporting member for the corresponding color light with the surface where the wire grid is not formed facing the first surface of the supporting member and the surface where the wire gird is formed faces the wire-grid polarizer fixing spring member (plate spring member), the plate spring member comes into contact with the surface where the wire grid is formed. The configuration in which the plate spring member comes into contact with the wire grid tends to cause the wire grid to be chipped or otherwise become defective, which degrades the quality of the wire-grid polarizer (wire-grid reflective polarizing plate). Further, JP-A-2008-180856 does not describe any angular adjustment of the wire-grid polarizer (wire-grid reflective polarizing plate) relative to the reflective spatial light modulator (reflective light modulating device).
It has therefore been desired to develop a reflective polarizing plate apparatus, an electro-optic apparatus, an optical apparatus, and a projector capable of not only maintaining optical characteristics of a reflective polarizing plate and reliably fixing the reflective polarizing plate against an impact or vibration by appropriately pressing the reflective polarizing plate but also angularly adjusting the reflective polarizing plate relative to a reflective light modulating device and improving the contrast by the angle adjustment.